Known self-propelled civil engineering machines, which include in particular road milling machines, road recyclers and road stabilisers, have a working arrangement to carry out the civil engineering operation of the civil engineering machine. The working arrangement may for example be a milling arrangement and in particular a milling drum.
Civil engineering machines of this kind differ from motor vehicles, and in particular from private cars, in that the civil engineering machine can be steered both with the front wheels or other running-gear units and with the rear wheels or other running-gear units. The positions assumed by, i.e. the steering angles of, the front and rear wheels or other running-gear units may be in the same direction or in opposite directions in this case. If the front wheels or other running-gear units and the rear wheels or other running-gear units are steered in opposite directions, the civil engineering machine is able to travel through a tight curve whereas the civil engineering machine is able to travel with a sideways displacement if the front and rear wheels or other running-gear units are steered in the same direction.
The stipulating of different steering angles allows the driver of the machine to move the civil engineering machine exactly over the terrain. When the civil engineering machine is being moved backwards however, the driver is faced with the problem that it is difficult for him to see the rear part of the machine. It is true that the civil engineering machine is only operated in the forward direction during the normal course of work but for it to be loaded, positioned to start work or parked, the driver usually has to reverse the civil engineering machine in a confined space. machine is intended to have himself directed by a second person when travelling backwards. Travelling backwards is nevertheless difficult because there are limits as to how much of the rear part that the driver can see. There are also known self-propelled civil engineering machines which have a camera at the rear end and a screen at the driver's station. The driver of the civil engineering machine can thus see the rear part, but even with a camera, it is difficult to estimate how the civil engineering machine is moving as it travels back.
For motor vehicles, and in particular for private cars, there are known arrangements which assist the driver when parking the vehicle. Such arrangements are also referred to as driver assistance systems.
DE 103 34 613 A1 describes an arrangement for motor vehicles which, as a function of the steering angle to which the wheels are turned, indicates the region for the movement of the vehicle, which is also referred to as a travel tube, on a screen. A driver assistance system for tractor vehicles with trailers is known from WO 2008/012109 A1.
The known driver assistance systems for cars and lorries are not suitable for self-propelled civil engineering machines which can be steered both with the front wheels or other running-gear units and with the rear wheels or other running-gear units. The adjustment of the chassis of the machine in the heightwise direction and to give a longitudinal or transverse inclination also makes special demands on a driver assistance system in self-propelled civil engineering machines.